Awareness key in stopping resistant weed spread

Even though the weed being referenced does include “hemp” in
its name, it’s not even close to be a recreational weed or a weed of choice for
Midwest farmers.

“The question I always ask growers is — do you want weeds or
do you want beans? In order to manage these weeds, we do have chemistries that
even the beans have to metabolize, so occasionally we do see some responses,”
said Doug Jones, retail account manager for northern Illinois for DuPont Crop
Protection.

Jones spoke at a field tour for local farmers and DuPont
Crop Protection agents at DuPont’s Midwest Research Farm near Rochelle.

He said farmers with resistant weeds should take a hard
line.

“The bottom line is — burn it down. Put the 2,4-D in the
tank. If you want to get good weed control, you’ve got to burn everything down
and 2,4-D will do that for you,” he said.

Resistant Weeds

Jones, along with the speakers before him, Dave Roome and
Wesley Shupe, promoted the concept of vigilance, monitoring and layering
residual herbicides as steps to take against glyphosate-resistant weeds such as
waterhemp, marestail and Palmer amaranth.

Roome reminisced over older chemistries with names
unfamiliar to most of the under-40-something farmers in the room.

“How many of you remember dealing with cyanazine (Bladex),
Linuron, dinitroanilines, those classes of chemistries?” he asked the farmers.

A few hands went up.

“It’s pretty limited if you look around the room anymore.
Some of us old guys dealt with some of those old chemistries. They were very
effective. They were probably the reason why we didn’t build a lot of weed
resistance 20, 30, 35 years ago. We rotated through different classes of
chemistry,” Roome said.

He said the opportunity does exist to get a handle on
glyphosate-resistant weeds, and he emphasized the need for attention and urgency
in dealing with the spread of those weed species.

“The sky is not falling. I’m not trying to build that. What
I’m trying to say is we need to have urgency around our awareness and what we
have in our surroundings, your fields, your neighbor’s fields, whatever it might
be because it’s exploded — from 2002 when you have just one species to 2012 and
down here in the deep South where you have as many as eight different weeds that
are resistant to glyphosate,” he said.

Hand
Weeded?

Roome said the financial impacts of non-herbicide
elimination of glyphosate-resistant weeds have been felt in the South, where
fields often have to be weeded by hand.

“Some of you remember walking with a bean hook, but we sure
don’t want to go to that stretch. People will show you pictures from the deep
South where they have hay wagons that are mounded full of the stuff that they
hand weed and haul to the edge of the field to burn. It’s $75 to $100 an acre to
do that,” he said.

Roome said careful and consistent observation of fields can
make the difference between success in eliminating the resistant weeds and
failure.

“We have to be aware of our surroundings and what we’re
dealing with. The weeds are so prolific in their seed production that you can
all of a sudden go from nothing to failure overnight,” he said.

However, all is not lost.

“How do we stop this trend? We try to build some layers into
it,” Roome said.

Palmer
Amaranth

And nobody is more familiar or able to talk about how and
what and when to build those layers than someone from an area of Illinois that
has experience in dealing with the most notorious of those resistant weeds —
Palmer amaranth.

“The moral of the story is — you’re going to have it,” said
Wesley Shupe, technical sales agronomist for southwest Illinois.

“You guys plant corn so if they can have it in soybeans, can
you have it in corn? It’s just a matter of time,” he said.

Shupe talked specifics about the layering approach for
herbicides to combat the resistant weeds.

“The value of a fall-applied herbicide is we’re tricking it.
We’re trying to keep it at bay. You’ve got to have that residual that works on
waterhemp or Palmer amaranth. You can’t be blowing it on in March or the first
week of April,” he said.

Timing is the key to successful layering, Shupe said.

“Ultimately you’ve got to be basing your residuals, basing
your second applications, from the time you put on your pre-emergent herbicide,”
he said.

Size matters, too, when trying to control Palmer amaranth.

“Dr. (Bryan) Young at Purdue will tell you — give weeds the
finger,” Shupe said, referencing Young’s method of measuring weeds using a
finger.

Once resistant weeds such as Palmer amaranth or waterhemp
are bigger than finger-size, Young has said, the weed control has failed.

“Help yourself out, put on a full rate of herbicide. The
reason why is because of the rate of growth of Palmer amaranth and timing, a
two-inch plant versus a six-inch plant is the difference between a clean field
versus a dirty field,” Shupe said.

“What you’ve got to do with Palmer amaranth is you can’t let
it get up. Once it gets up, you’re going to play heck to control it.”

Doug Jones, Shupe’s counterpart for northern Illinois,
wanted to do show and tell.

“I was going to bring a Palmer plant up in a big glass case
with locks and chains,” he told the audience, but added that idea was nixed by
the farm’s manager.

“The bottom line is — we do have some of it up here,” he
said.

Jones said growers will have to decide whether to have weeds
or soybeans with some possible burning.

“What do we do now? We don’t have a lot of options. You’ve
got to go out there with a burn, like a Cobra or an Ultra Blazer. We have to go
back to the days of burning our beans,” he said.

Jones said that in the end, layering provides an effective
way to combat the issue of glyphosate-tolerant weeds.

“Layer the chemistry, we need to get the residuals out
there. Get away from the glyphosate-only types of applications. Get away from
these issues we can’t fix,” he said.